The present invention is particularly applicable but not necessarily restricted to an apparatus and method for processing cup-shaped workpieces, such as containers employed for packaging various products such as foodstuffs, including beverages, and other products such as paints, deodorants, insecticides, etc., which are dispensed in pressurized aerosol-type containers. High-speed, modern, automatic machines have been developed for forming such containers in any one of a variety of materials including glass, plastic materials, metal and metal alloys such as, for example, tin-plated steel, plastic-lined steel, aluminum and alloys thereof.
It is customary in the packaging art to subject the preliminarily-formed containers to a series of treatments preparatory to the filling operation in which surface contaminants, such as die lubricants and other films deposited during the fabrication process, are removed to render the containers of the requisite cleanliness, as well as to impart selected surface treatments to the containers in order to increase their corrosion resistance, to provide a desired decorative appearance and to render the container surface more receptive to a final finish coating. It is necessary to effect such plural treatments of the containers at high speed corresponding to the rate at which the container bodies are fabricated and this has occasioned problems in the processing of cup-shaped containers because of their tendency to entrap a treating solution from one treating step causing a carry-over thereof and a contamination of the treating solutions of succeeding treating steps. Another problem associated with high-speed processing of containers has been the tendency of a stagnant liquid film to form adjacent to the workpiece surface which becomes depleted of the active agents therein during the course of a treatment, thereby reducing the speed and efficiency of the treating cycle.
The apparatus and method of the present invention overcomes the problems and disadvantages associated with prior art techniques by substantially eliminating the formation of stagnant surface films on the workpiece surface, thereby optimizing treating efficiency and further assuring a substantially complete removal of residual treating liquid from the surfaces of the container before initiation of the next treating cycle.